1. Field of the Invention
The present invention relates to the field of electromechanical circuits or microsystems (MEMS). These circuits are especially used in mobile phone radio frequency applications.
2. Discussion of the Related Art
WO01/13457 discloses a switch having a beam embedded at an extremity, including a piezoelectric actuation means formed of a unit disposed on a portion of the mobile beam. This unit is made of a plurality of layers parallel to the surface of the beam. The first layer is a conductive electrode, the second layer is a piezoelectric layer (PZT), the third layer is a second conductive electrode. When an electric voltage is applied between the first and second electrodes, the unit expands in the direction of the length of the beam. Therefore, a bi-metal effect appears between the beam and the piezoelectric unit that causes a bending of the beam. This structure is difficult to manufacture and necessitates a large number of steps for depositing the different layers one above the others.
Additionally, EP Patent Application 0963000 discloses an electrostatically actuated mechanic microswitch and a resonator assembled in the same device. The actuation mode is not suitable for a large number of applications and the use of a piezoelectric actuator of the above type in such a device may result in a complex structure.